The influences of naphthalene-based plasticizers and polycarboxylate acid/salt super plasticisers on creep of concrete, including basic creep and drying creep, were investigated. Internal relative humidity and pore structure of concrete and the surface tension of pore solution were tested. The results show that polycarboxylate acid/salt super plasticizers refine capillary pores in concrete and reduce surface tension of pore solution. In addition, restrain internal moisture transmission and redistribution. As a result, creep of concrete is reduced. Compared with naphthalene-based plasticizer, poly carboxylate acid/salt super plasticizer causes a greater reduction of drying creep, but a smaller reduction of basic creep. This is because the moistures redistribution is quite feeble and quickly balanced in sealed condition. Concrete with poly carboxylate acid/salt super plasticizer has the lowest creep value because poly carboxylate acid/salt super plasticizer improves hydration degree and reduces porosity of macro pores.